Scanning device



Nov. 23, 1937. M. M. STERN ,872

SCANNING DEVICE Original Filed Feb. 26, 1954 5 Sheets-Sheet 1 INVENTOR MILTON M. STERN BY 4% M ATTORNEY Nov. 23, 1937. M. M. STERN SCANNING DEVICE Original Filed Feb. 26, 1934 3 Sheets-Sheet 2 w Q H INVENTOR MILTON M STERN ATTORNEY Nov. 23, 1937. M. M. STERN 2,099,872

SCANNING DEVICE Original Filed Feb. 26, 1934 5 Sheets-Sheet 3 INVENTOR MILTON M. STERN ATTORNEY Patented Nov. 23, 1937 UNITED STATES PATENT QFFEQE SCANNING DEVICE Milton M. Stern,

Los Angeles, Calif.

7 Claims.

My invention relates to a scanning device suitable for use in television.

Although the present invention is suited' for 5 use with many methods wherein an image is disintegrated at one point and then assembled or integrated at another point, the principal utility at present perceived for the invention is in television, and it is therefore thought that the purpose of disclosing the features thereof may be best served by limiting the description and drawings to forms of the invention expressly designed for television use.

The detail or definition to be obtained in a scene or image transmitted by television depends upon the number of lines into which the image is divided. Present structural characteristics appear to impose definite limitations upon the number of lines which may be produced on a given area. The principal object of my invention is to provide a device which will produce a large number of lines on a given area, which device constitutes a marked simplification over the art as it is now practiced, and which may be relatively economically manufactured and likewise easily operated.

An object of the invention is to provide a method of scanning, which consists in the movement of a mirror or a plurality of mirrors relative to two angularly disposed axes, in such a manner that an image may be disintegrated and the light values of the different parts thereof transformed into other forms of energy, such as electrical modulations, and whereby such modulations of energy may be subsequently impressed upon a light beam fluctuating in accordance with the modulations, which light beam may be reassembled or integrated into the form of a projected image in duplicate of the original image.

It is an object of my invention to provide a method and means of scanning, wherein images may be transmitted with such rapidity that the motion of the consequent elements of an image will be clearly and smoothly shown in the reproduction or projection of an image on a screen.

It is a further object of the invention to provide a scanning device having a plurality of light directing elements, such as mirrors or reflectors, disposed so as to revolve around a primary axis and also relative to a secondary axis disposed at an angle to the primary axis. The simple form of the invention consists of mirrors placed on a body so as to define a cylinder. As this body is rotated so that the mirrors will revolve around the axis thereof, the beam of light reflected by each mirror as it passes through a position to receive a projected beam will swing through a plane transverse to the axis of the body, the plane or path of the reflected beam produced by each of the mirrors coinciding. In order to oifset the paths of the consecutive beams, means are provided for relatively slowly rotating the body on an axis which is preferably perpendicular to the axis of the body. In the preferred practice of my invention, however, the reflectors are curved in such a manner that the end portions thereof converge toward the axis of rotation around which the mirrors revolve.

It is a further object of the invention to provide a simple means for producing a composite rotation of the refiectors, comprising a pair of synchronous motors, one of which is disposed within the body upon which the mirrors are mounted.

It is a further object of the invention to provide a device of the character set forth in the preceding paragraph, in which the mirrors are mounted upon a hollow motor rotor disposed around a central stator.

Further objects and advantages of the invention will be made evident throughout the following part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a somewhat diagrammatic view showing a simple form of my invention and a manner of its use.

Fig. 2 is a side view for illustrating the effect produced by one of the movements of each reflector.

Fig. 3 is a schematic plan View showing the effect produced by the secondary movement of each reflector.

Fig. 4 is a perspective View showing the preferred form of my invention, in which the refiectors are curved so as to define a body of oval cross section.

Fig. 5 is a vertical cross section, to enlarged scale, through the scanning device shown in Fig. 4.

Fig. 6 is an elevational view showing an alternative method of driving the scanning device.

In Fig. 1, which is employed for exposing the general principles of my invention, I show primary and secondary light beams I0 and II, either one of which may be considered a reflection of the other, depending upon whether the device is used for disintegrating or integrating an image. The form of scanning device shown in Fig. 1 includes a cylindrical body 12 carried by a yoke l3 so as to rotate on a primary axis A-A, such yoke 13 being supported upon a casing 14 in a manner to rotate on a secondary axis BB. As'

will be hereinafter clearly shown, there are several means whereby the body l2 maybe driven so as to rotate on the axis A A and whereby the yoke 13 may be rotated on the axis BB,

" sist of flat reflective faces formed directly upon of the screen l8.

the'body l2 or by the applicationof strips or mirrors of strip form to the surface thereof. In the simple practice'of. the invention the reflectors l5 are flat and are elongated with respect to the axis.A A, as well as being disposed parallel and tangential with relation thereto. pose of explanation, let it'be assumed that the beam H is originatedin a light produci means 9 which in television embodies means for modulating, such light beams in accordance with a pattern received froma television transmitting station. The light beam II is projected toward the body l2 so that as the reflectors l5 revolve aroundthe axis A- -A,. they will consecutively intercept the beam H and reflect such beam, ll so as to produce a reflected beam I ll. The beam H being stationary, the change in the angular relation of each reflector l5 relative thereto will cause. the reflected beam I to swing through a' planewhich is transverse to the primary axis AA.. Accordingly, if a screen [8 is set up so as to intercept the beam H], such beam I0 will travel across the screen nearly vertically and will inscribe a line or path 20 thereon.

Illustrative of this, I have shown a reflector l mounted upon a cylinder l2 so as to rotate on the axis of the cylinder indicated by the letter A. With the reflector l 5 in the position in which it is shown in full lines in Fig, 2, the incidental beam H will be reflected and produce a beam Illa extending from the mirror l5 to the screen l8. As the cylinder or body I2 rotates in anticlockwise direction, the angle of incidence of the beam H relativeto the mirror will change so that as the reflector l5 rotates downwardly, the reflector beam of light will'pass through the consecutive positions lob, lilc, and will finally reach the position Hid when the reflector 15 reaches the position indicated by dotted lines I511. Accordingly,.the reflected beam of light will transcribe a path or line on the screen. Now, if the yoke I3 is held stationary, each of the mirrors [5 will reflect a beam lilthrough the same plane orpath as the reflected beam above described, and the consecutive beams will all transcribe a line 20 on the screen l8 in the same position. By relatively slowly rotating the yoke i3, and likewise the system of reflectors IE, on the secondary axis BB, I cause the reflected light beam Ill produced by each consecutive mirror to be laterally offset relative to the preceding light beam so that each consecutive light beam will transcribe its own line or path 20 on the screen l8.in' a position adjacent the preceding line 20. The result of this composite rotation of the reflectors I5 is the inscribing of separate paths or lines of light from 'oneedge to'the other .Whether these lines '20 are to extend vertically or' longitudinally depends upon the longitudinal or vertical positioning of the axis A-A. .With the axis A-+A in a hori zontal plane as shown in Fig. l, the lines 20 will be. formed vertically upon the. screen l8. By turning the axis B-.B. from vertical to hori- For purzontal position, horizontal lines 26 may be pro duced upon'the-screen. To cleariy illustrate the secondary movement of the reflectors !5, I have in Fig. 3 shown the body l2 in plan view, in such position that the incidental beam" II will be reflected by one of the reflectors so as to produce a reflected beam Ille in an approximately vertical plane coinciding with the edge H of the screen l8. As the body 12 revolves in'clockwise direction on the secondaryiaxis indicated by B toward the dotted line position 22, the succeeding reflector l5will reflect a beam it; through a,

nearly vertical plane adjacent the plane of 'th'e.

.beam Inc, and as the secondary movement of" V the body I2. continues in timed relation to the primary rotation'thereof, each consecutive reflector [5- will swing horizontally through a small 7 angle around the secondary axis indicated by B in Fig. 3 and BB in Fig. 1, and consequently the vertical planes through which the reflected I beams pass will be offset in horizontal direction in a regular manner from one side tothe other of the screen I8. Thefo'regoing action of producing vertical. lines from one side to the other of the screen |8 is considered a single frame in motion picture and television projection'in that plete image. frame; the rotation of the body l2 on the axis BB continues in clockwise direction through a I drawn upwardly.

It is important to note that the downward drawn lines and the upwarddrawnlines 'areinclined in opposite directions so that when the 7 linesof two consecutive frames are superimposed, V the lines of one frame intersect the lines of the 5:

other. As a result of the intersecting, the linear effect of scanning is less apparent'than usual to the observer and a better image is obtained by a .given number of lines than may be obtained without such intersecting. The intersecting effect is made possible by the fact that the reflecting body rotates completely about its secondary axis. 7

Thus, in Fig. 1, aswell as in Fig. 4, Whenthe mirror rotates in the direction indicated by the solid arrow, the screen is scanned diagonally as indicated by the inclined solid lines} when the secondary axis has beenrotated :to cause' the mirrors to rotate in ,the direction indicated by the dotted arrow, the screen is scanned as indicatedby the inclined dotted lines.

From the foregoing it will be perceived that .the position of the beam i 8 is determined by the position of a mirror or reflector l5 cooperating thereit constitutes a taking or formationof a'comf After the completion of the single with. Accordingly, light may start from a point a P on the screen l8, Fig. l, and pass through the beam ll) to the reflector indicated specifically as l5a and then be reflected through the path of the beam I l;to the device 12 which may consist in this use of the invention of a means for modulating an electrical flow in accordance with the m'odula tions of light received thereby. Accordingly,. if

the screen l8 has a picture or image thereon,and such'screen lfiislightedso that light will be reflected from the image on the screen i8 to the scanning devicesuch canning evi tmtq eh t ecomposite rotary movement of the reflectors I5 thereof,'wil1 segregate lines of light from the image on the screen it, or, in other words, will disintegrate the image and reflect the same to the device 12. This practice of disintegrating or scanning an image is what is known as the camera method. The device shown in Fig. 1 may be employed in other manners of scanning, such, for instance, as the flying spot method. In other words, the characteristic movement of the reflectors l 5 results in the defining of prescribed paths l and H through which light energy may flow to or from the member l2, the path II being always fixed and'the path iii being constantly in motion in the characteristic manner hereinbefore described, so that the leftward end of the path It transcribes consecutive lines on the screen l8 regardless of whether light is being taken from the screen It or is being projected thereonto.

t will be perceived that the relative speeds of rotation of the member i 2 on the axes A--A and BB must be determined in accordance with the movement of reflectors l disposed around the axis of rotationA-A. The rotation may be accomplished by gear trains or by mounting a motor in the casing l4 and a second motor within the body l2, these motors being operated in synchrony so as to produce clesiredspeeds of rotation around the axes AA and BB. In Fig. 4 I show a modified form of the invention employing a vertically disposed motor 36 having a yoke 3| mounted on the upper end of its shaft 32. Secured in the upper ends of the yoke is an axle member 33 which supports, as shown'in Fig. 5, a'motor stator 34 around which a rotor 35 is assembled. Through the use of brushes 3B, electrical energy is transmitted to rings 37 mounted upon the yoke 35. Electrical energy is then carried from the rings 37 by means of conductors 38, through one of the arms 49 of the yoke 3!, and through openings 4! in the shaft 32 into the motor stator 34 which cooperates with the rotor 35 to form a motor 42.. The motors 5i] and 42 are of synchronous type and. being energized from the same source of alternating current, will operate in synchrony at the respective speeds for which they are designed.

Qn the rotor 35 of the motor 42 a ball-like shell 43 consisting of cooperating parts 44 and 45 is mounted, the outer portion of the member or body 43 having light controlling or directing means 46 formed thereon which preferably consist of reflective faces or reflectors which are elongated in the direction of the axis of rotation A-A defined by the axle 33, are tangential With respect to such axis, and are so curved that the ends thereof converge with respect to the axis A-A. The faces or reflectors 46 due to their curvature, as described, must have a characteristic shape which may be referred to as lemon peel shape. These faces 46 are widest at the centers thereof and are gradually reduced in width toward the ends thereof. The body 43 rotates relative to the axes AA and BB as does the body l2 of Fig. 1, and the reflective faces 46 have the same function as the reflectors l5, in that they, by the characteristic change in the angular posi tion thereof, produce a definite relation between beams or paths I8 and H in such a manner that the leftward end of the path If! will transcribe consecutive adjacent lines offset laterally across the screen or image i8. By curving the reflectors or reflecting faces 46, the time lapse between consecutive frames or images may be materially reduced, and accordingly the form of rotating body 43 shown in Figs. 4 and 5 is believed superior to the simple cylindrical form shown in Fig. 1, since a greater rotation of the body 43 on the axis BB is required to produce the change in the angle of reflection necessary to carry the consecutive light beam I5 laterally across ,the screen l8. It will be recognized that the curvature of the reflecting faces 45 will vary with the Width of the screen l8, and that the curvature for any given condition of operation may be readily determined either experimentally or mathematically.

By virtue of the fact that the mirrors are curved to converge at their ends, light is reflected toor from the screen or image i 8 during a greater number of degrees of rotation of the reflecting body about its vertical axis than would be possible were the reflecting surfaces not convergent. Consequently, the dead interval between frames required for transition past the ends of the mirrors is greatly reduced. It is also tobe noted that since curving of the mirrors reduces the ratio between the rate of lateral movement of the beam and rate of rotation of the mirrors about the secondary or vertical axis, closer scanning for a given rate of such rotation is achieved.

In Fig. 6 I show an alternative method of producing a desired composite rotation of the reflector body 43 or any other type of reflector body coming within the teachings of this disclosure, such, for instance, as the cylindrical type shown in Fig. 1. In this practice the body 43 is supported in a yoke 50 by means of axles or trunnions 5!. On a line perpendicular to the'primary axis defined by the trunnions 5i a shaft 52 extends downwardly into a driving mechanism 53 which may consist of a synchronous motor, thereby providing means for rotating the ball 43 on a secondary axis. Mounted on the motor 53 is a gear 54 which is held stationary and concentric relative to the shaft 52. A vertical shaft 55 is extended upwardly through one side of the yoke 50 and has gears 56 and 57 on the ends thereof, the gear 56 rolling in engagement with the gear 54 as the yoke 58 is turned and transmitting rotation through the shaft 55 and the gear 51 to a gear 58 mounted on one of the trunnions 5!. Accordingly, each rotation of the yoke 55 on the secondary axis defined by the shaft 52 will, through the gears shown, cause a faster rotation of the body 43 on the primary axis defined by the trunnions 5|. As hereinbefore stated, the relative speeds on the primary and secondary axes are controlled by conditions under which the apparatus is to be employed, such for instance, as the size of the screen with relation to the distance of the screen from the scanning device.

I believe that by use of my invention a much greater number of lines in an image can be obtained than has heretofore been accomplished. For example, I may with ease obtain 200 lines and without difliculty should exceed 400 lines when the progress of the art of television may demand the same, as compared with the approximate 120 lines now employed in television images,

I claim as my invention:

1. A device of the character described, includ-- ing: a primary part mounted so as to turn on a primary axis; a plurality of reflectors disposed on said primary part around said primary axis, said reflectors being elongated in the direction defined by said primary axis, an end portion of each of said reflectors being converged toward said primary axis; means for giving said primary part rotary movement completely around said primary axis; and means for giving sai-d primary part rotary movement completely around a secondary axis disposed at an angle to said primary axis in a timed relation to the' rotary movement of said primary part relative to said primary'axis,

2. A device of the character described, includ- 7 ing: a primary part'mounted so as to turn on a primary'axis; a plurality of'refiectors disposed on" said primary part around said primary axis, said reflectors being elongated in the direction defined by said primary axis, and said reflectors being curved so that the ends thereof are'converged toward said primary axis; means for giving said primary part rotary movement relative to said primary axis; and means for giving said primary part rotary movement on a secondary 'axis passing centrally through said primary part posed intersecting axes; light directing elements I carried by said member; means for continuously rotating said member about one of said'axes;

and means for simultaneously continuously ro-' tating said member about the other of said axes,

whereby the field to be scanned is successively scanned in a plurality of substantially parallel 'lines with the'lines of successive scannings angularly disposed.

4. Ascanning device, comprising: a member 7 mounted for rotation about two angularly dis posed intersecting axes; light directing elements carried by said member and arranged thereon circumierentially with respect to one of said axes; means for continuously rotating said member about one of said axes and means for simul- 7 taneously continuously rotating said member about the other of said axes, whereby the field to be scanned is successively scanned in a plu rality of substantially parallel lines with the lines of successive scannings angularly disposed.

5. A scanning device, comprising; a member mounted for rotation about a primary axis; a plurality of light directed elements carried by said member and circumferentially disposed about said primary axis; means for continuously rotating said member aboutsaid primary axis;

and means for supporting said member adjacent, said primary axis and simultaneously con: tinuously rotating said member in timed relation .with the rotation about said primary axis about asecondary axis angularly. disposed with respect 7 to and intersecting said primary axis; whereby the field to be scanned is successively scanned in a plurality of substantially parallel. lines with the lines of successive scannings angularly disposed.

6. A scanning device, comprising; a member mounted for rotation about two perpendicularly disposed intersecting axes; light directing elements carried'by said member and circumferentially disposed about one of said axes; means for continuously rotating said member about one of said axes; and means for simultaneously con-. tinuously rotating said member about the other of said axes, whereby the field to be scanned is successively scanned in a plurality of substantially parallel lines with the lines of successive 'scannings angularly disposed.

'7. A scanning device, comprising; a member mounted for rotation about a primary axis; a

plurality of light directing elements carried'by said member and circumferentially disposed about said primary axis; an electric motor positioned within said member for continuously rotating saidmember about said primary axis; a support for said member mounted for rotation about a secondary axis perpendicularly disposed with respect to and intersecting said primary axis; and means for simultaneously continuously rotating said support about said secondary taxis, whereby said member is simultaneously continuously rotated about said primary and secondary axes to scan a field in a plurality of substantially parallel lines with the lines of successive scannings angularly disposed.

' MILTON M. STERN. 

